1. Technical Field
The present disclosure relates to a backlight assembly, and more particularly, to an optical plate, a backlight assembly and a display device including the same.
2. Discussion of the Related Art
Generally, a liquid crystal display apparatus (LCD) is a display device displaying an image using liquid crystals having optical and electrical characteristics of anisotropy in a refractive index, and anisotropy in a dielectric constant. The LCD is slim and lightweight and has a low driving voltage and low power consumption compared to other display devices such as cathode ray tubes (CRTs) and plasma display panels (PDP). Accordingly, the LCD is widely used as a display device in a variety of products.
The LCD includes a liquid crystal (LC) display panel including a thin film transistor (TFT) substrate, a color filter substrate facing the TFT substrate, and an LC layer interposed between the two substrates to change light transmittance. Also, since the LCD is not a self-luminous device in which an LC display panel displaying an image can emit light spontaneously, the LCD uses a backlight assembly supplying light onto the LC display panel.
A related art backlight assembly includes a lamp generating light, and a light guide plate (LGP) guiding light incident from the lamp disposed at a lateral side to an LC display panel. The LGP is categorized as either a flat type LGP or a wedge type LGP. In the flat type LGP, an incident portion into which light is incident and a counterpart portion which is opposite to the incident portion have the same thickness. In the wedge type LGP, the thickness of the LGP reduces toward the counterpart portion.
Recently, to prevent discoloration of the LGP and to improve brightness of the LGP, a prism LGP where a prism pattern is formed in the surface of the LGP has been developed. In case of a flat type LGP having the same thickness, light guided inside the LGP satisfies a total internal reflection condition, so that the light is emitted to the outside by the prism pattern.
However, in the case of the LGP where the prism pattern is formed, when external physical pressure is applied to a final product using the LGP, the LGP may be forced into contact with other optical members used by the LCD. For example, the LGP may be forced into contact with a prism sheet used to change a light path. Such contact may result in a white screen phenomenon whereby the light path in a medium, for example, air between the LGP and the prism sheet is obstructed due to contact of the LGP and the prism sheet, and light is not refracted but emitted at a low angle, and directly viewed.
In a related art, to resolve this white screen phenomenon, beads are coated and pressure is applied on the surface of the prism sheet facing the LGP to minimize a contact area with the LGP. However, use of the beads may contribute to a haze phenomenon, and brightness of the display may be reduced.